Layka, the dog pictured on our cover and here, was two when she was sent to help clear an enemy compound in Afghanistan. During her search she was shot by enemy forces and took four rounds from an AK-47 at point-blank range. Despite her injuries, she attacked and subdued the shooter, protecting her handler, Staff Sgt. Julian McDonald, and other members of the team. It took seven hours of surgery, including the amputation of a limb, to save her. In 2012 Layka was presented with a medal of heroism and adopted by McDonald, who now trains dogs and their handlers at Fort Benning, Georgia.

Our cover story, “The Dogs of War,” is about a special bond. Dogs have been our best friends for at least 14,000 years. The relationship is in our genes and theirs. When it comes to the dogs of war, the stakes couldn’t be higher. The penalty for a misstep by either partner can be injury or death. The U.S. military deploys more than 500 dogs worldwide at any given time. Each year a few are killed in action.

When Layka bounded out of the van that delivered her to Sergeant McDonald’s home—a special brace allows her to run as if she’d never lost a leg—she instantly recognized him, even though they’d been together only a month before she was shot. “Her excitement brought me to tears,” McDonald says. “She was the sole reason why I was living and breathing and able to come home to my son and wife.”